1. Field of the Invention
The present invention relates to a neuro-computer capable of simulating large-scale neural networks constituted on the basis of a neuron model by using parallel processors.
2. Description of the related Art
A high speed general purpose computer is used in order to simulate large-scale neural networks constituted on the basis of a neuron model. However, it takes considerably long time to simulate the learning process of even small-scale neural networks. Therefore, it takes several weeks to simulate the learning process of intermediate scale neural networks. Therefore, the parallel processings using multiprocessors have been introduced recently in order to obtain the high performance. Various models of the neurons have been developed, however only one type of neuron model is usually used in a neural network, and it is rare to use a plurality of models in a neural network. As described above, since the same calculations are executed for simulating neurons in a neural network, the simulation of a neural network is considered to be a suitable for parallel-processing. Therefore, the simulations using a general purpose parallel computer have been attempted. Since the large-scale neural networks include a large amount of connections between neurons, it is a critical factor to select a method of connecting the processors in the case where the simulation is done by multiprocessors. There have been developed various systems such as a mesh type (a lattice type) connection, a cross-bar connection, a tree type connection, a multilevel cross type connection, a cubic type connection, and the like as the method of connection in the parallel computers. In particular, the tree type connection, the multilevel cross-bar type connection, and the cubic type connection are considered to be suitable for simulating the neural networks. However, when the number of the processors is increased, it arises the problems such as a number of switch circuits becomes large, the capacity of the transmission becomes short, and the increasing number of the line intersections causes the implementation to be hard. Therefore, a method of connecting the processors in a parallel-processing for the efficient simulation of the neural networks has not been established.
Since the neural networks consist of the neurons of the same type, a high speed simulation is expected on the parallel processing of multi-processors. However, there are many connections in large-scale neural networks which correspond to the synapses of neurons and the number of the connections is increased in substantially proportion to the square of the number of neurons. Therefore, in the case where the whole neurons are divided into a proper number of groups, each of which has a processor and a simulation is executed by multi-processors, the connections for transmitting information between the processors are necessary since there are connections between the neurons in each of the groups. When the number of the processors are increased in order to raise the performance, the number of the connections between the processors is increased in substantially proportion to the square of the number of the processors. Furthermore, for high speed transmission between the processors, the transmitting capacity must be enlarged and the transmitting speed must be raised by providing parallel transmission lines. That is, when the number of parallel processors are increased for the high speed simulation, the number of the connections between the processors will be increased excessively, causing to make the implementation impossible.